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Biomedical subjects

A A Zinchenko

Publications and source records attributed to A A Zinchenko.

At least 19 recordsLinked to original sources
PubMed2006

Development and validation of reversed phase high performance liquid chromatography method for determination of dexpanthenol in pharmaceutical formulations.

This paper describes the validation of an isocratic HPLC method for the assay of dexpanthenol in aerosol and gel. The method employs the Vydac Proteins C4 column with a mobile phase of aqueous solution of trifluoroacetic acid and UV detection at 206 nm. A linear response (r>0.9999) was observed in the range of 13.0-130 microg mL(-1). The method shows good recoveries and intra and inter-day relative standard deviations were less than 1.0%. Validation parameters as specificity, accuracy and robustness were also determined. The method can be used for dexpanthenol assay of panthenol aerosol and gel with dexpanthenol as the method separates dexpanthenol from aerosol or gel excipients.

Aerosols↗
PubMed2000

Interplay between folding/unfolding and helix/coil transitions in giant DNA.

It has been well established that double-stranded DNA undergoes a melting, or helix/coil, transition into a single-stranded coil state with an increase in temperature. On the other hand, it has recently been found that, at a fixed temperature, long DNA, larger than several kilobase pairs, exhibits a discrete transition, or switching, between elongated and folded states, preserving its double-stranded structure, with the addition of various condensation agents, such as alcohol, hydrophilic polymer, multivalent cation, and cationic surfactant. In the present study, we examined the interplay between the folding/unfolding transition and the helix/coil transition in individual giant DNA molecules, by observing the conformation of single molecular chains with fluorescence microscopy. The results indicate that the helix-to-coil transition tightly cooperates with the unfolding transition in DNA.

Circular Dichroism↗
PubMed2000

[A noninstrumental Immunoassay based on colloidal dyes].

Detecting labels based on water dispersions of colloidal textile dyes were developed that are useful in various analytical and diagnostic test systems for a simple visual assessment of the assay. Colored water-insoluble particles of dyes were used for the sorptional immobilization of streptavidin on their surface. The resulting streptavidin-dye (STR-DYE) complexes possessed a high visualizing capacity and were used for the combined detection of pesticides (simazine and 2,4-dichlorophenoxyacetic acid) by noninstrumental immunoassay (DYE-comb-assay, competitive dot-immunoassay in the comb format). The detection limits and the duration of our DYE-comb-assay (4 ng/ml, 20-25 min), HRP-comb-assay (competitive dot-immunoassay in the comb format using the enzymic conjugate of STR with horseradish peroxidase) (16 ng/ml), and the traditional competitive ELISA (12-16 ng/ml, 1.5 h) were compared. This DYE-comb-assay is simple enough and can be used under field conditions.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1997

[Simple immunoassays of pesticides based on the biotin-streptavidin system].

A simple method was developed for the preparation of a highly active streptavidin-peroxidase conjugate that enhances fourfold the sensitivity of bioassays. Using this conjugate, a quantitative assay of simazine and 2,4-dichlorophenoxyacetic acid (competitive ELISA) and a noninstrumental express method for simultaneous detection of these pesticides (dot-immunofiltration assay) were developed. The detection limit of the pesticides is 3-4 and 2 ng/ml and the duration of the assays is 1.5 h and 5 min for ELISA and dot-immunofiltration, respectively. The express method is easy and straightforward and enables the assay to be performed outside the laboratory.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1990

Relationship between structure and histamine releasing action of polymyxin B and its analogues.

The relationship between the structures of polymyxins and their histamine releasing action on rat mast cells was studied. Analogues of polymyxin B (PB) had different hydrophobic properties, positive charge and peptide chains (deca-, nona- and heptapeptides). The biologic activities of cyclic and decyclic heptapeptides (analogues of PB), and polymyxin M and its decyclic form were investigated. Removal of some amino acid residues from the polymyxin peptide chain decreased but did not completely block its histamine releasing action. There a correlation between the hydrophobicity of the investigated compounds (calculated by Rekker's method) and their histamine releasing action. The native forms of polymyxin M and cyclic heptapeptide (analogue of PB) possessed a higher histamine releasing action compared to their decyclic forms. Modification of PB did not change its noncytotoxic secretagogue properties. These data suggest that hydrophobicity and the cyclic ring are important features in determining the histamine releasing properties of the polymyxins.

Amino Acid Sequence↗
PubMed1989

[The histamine-liberating action of polymyxin B and its analogs].

Histamine-releasing effect of polymyxin B1 and its deacylated analogues has been studied on purified rat mast cells. The structure-activity analysis showed that cyclic peptide fragment and acyl residue of molecule of polymyxin plays an important role in histamine-releasing activity. Histamine release, induced by polymyxin B1 and its analogue was blocked by metabolic inhibitor antimycin A. Preincubation of polymyxin B1 with lipopolysaccharide inhibits in dose-dependent manner polymyxin-induced histamine secretion from rat mast cells.

Animals↗
PubMed1989

[Structural and functional investigation of polymyxins. Structure and biological properties of polymyxin M analogs].

The effect of proteinases of plant and microbial origin on polymyxin M was studied. It was shown that this antibiotic was absolutely stable to the effect of papain and ficin. On hydrolysis with subtilisin there formed polymyxin decyclized analogs not described earlier. Their isolation, purification and biological activity are described. The structure of these compounds was assessed by one- and two-dimensional 1H NMR spectroscopy. The role of various functional groups, their space orientation and impact on antimicrobial activity of the compounds are discussed.

Ficain↗
PubMed1988

[The action of combinations of the nonapeptide polymyxin B with antibiotics on gram-negative bacteria].

Activity of polymyxin B nonapeptide alone and in combination with other antibiotics against clinical strains of Pseudomonas and enteric bacteria was studied. It was shown that nonapeptide was highly active against Pseudomonas and moderately active against enteric bacteria. In combination with rifampicin, fusidic acid or erythromycin the nonapeptide had a potentiating effect on the tested strains.

Anti-Bacterial Agents↗
PubMed1987

[Structural and functional research on polymyxins. 1H NMR analysis of the conformation of polymyxin M in water].

Spatial structure of polypeptide antibiotic polymyxin M in water was studied by one-and two-dimensional (COSY, COSY-45, RELAY) H NMR spectroscopy. Analysis of the signal spectral parameters revealed two intramolecular hydrogen bonds in the cyclic part of the molecule which was analogous to the structure of polymyxin B. However, configuration of both the beta-turns in the polymyxin M structure differed from that of the detected earlier beta-turns in the structure of polymyxin B.

Hydrogen↗
PubMed1987

[Formation of classical C3 convertase during the alternative pathway of human complement activation].

The fluid phase C3 convertase of the alternative pathway of human complement activation has been constructed from the isolated C3 component and from purified factors B and D. The enzyme was able to activate the isolated components C4 and C2 in the presence of C4 but had no effect on C2 in the absence of C4. The C4 and C2 activation was monitored by the loss of their hemolytic activity during the incubation with the alternative fluid phase C3 convertase. The activation of C4 and C2 components by the membrane-bound alternative C3 convertase formed on red cells (EC3bBb) was followed by the formation of C3 convertase of the classic pathway--EC4b2a. This resulted in the enhancement of hemolysis.

Animals↗
PubMed1986

[Inhibition of the binding and activation of the first component of human complement. The effect of synthetic peptides, immunoglobulin fragments and various proteins].

A study has been carried out on the inhibition of the subcomponent Clq binding to sensitized sheep erythrocytes (EA) by the following synthetic peptides mimicking the structure of a putative complement binding site of immunoglobulin G: Boc-Trp-Tyr, Boc-Tyr-Trp, Trp-Tyr, Boc-Trp-Phe, Boc-D-Trp-D-Tyr, Boc-D-Tyr-D-Trp, Boc-Leu-Leu, Ac-Phe-Tyr, and commercial Thr-Lys-Pro-Arg (tuftsin). Boc-Trp-Tyr was found to be the most potent inhibitor of Clq binding to EA (Ki 2.86 X 10(-4) M), tuftsin ranking second with Ki 6 X 10(-4) M. The D,D-dipeptides failed to inhibit the Clq binding at the investigated concentrations. Insoluble Z-Trp-Tyr-OMe activated a classical pathway of complement system, as monitored by consumption of C4, C2 and C3 components. Synthetic octapeptide Boc-Glu-Val-Asp-Leu-Leu-Lys-Asp-Glu-OMe (corresponding to the sequence 36-43 of beta 2-microglobulin) inhibited the Clq binding with Ki 4.7 X 10(-4) M, which gave grounds for localizing the complement binding site in beta 2-microglobulin. The finding in the Clq structure of the peptide sequence homologous to than of the pepsin active site, as well as the close similarity in the specificity of these proteins towards hydrophobic amino acid residues justified the assumption on the same structural bases of their specificity. The results of the present study, along with the literature data, underlie the hypothesis on the involvement in the complement binding of the following IgG residues: Trp277, Tyr278, Lys320, Lys322, Glu318 and Lys290. The enlisted residues are closely located in the three-dimensional structure of the CH2 domain of IgG. Lysozyme and lactalbumin having the sequences homologous to Trp277-Tyr278 of IgG inhibited Clq binding to EA with Ki 3 and 1.5 microM respectively.

Amino Acid Sequence↗
PubMed1985

[Changes in the ultrastructure of subcomponent C1q of human complement during spontaneous inactivation in diluted solutions].

Dilution of human serum or solutions of highly purified subcomponent C1q of human complement results in the drop of C1q activity. Electron microscopy of highly purified subcomponent C1q revealed that a certain part of molecules has a changed ultrastructure and C1q subunits are dissociated. As the preparations for electron microscopy have been obtained from dilute solutions, the changes in the ultrastructure and C1q inactivation should be interrelated phenomena. The conformational liability of the C1q structure is supposed to have a functional role.

Complement Activating Enzymes↗
PubMed1985

[Complement fixation activity of immunoglobulin G in ethylene glycol solutions].

Affinity of IgG to the first complement factor C1q was found out to increase in 10-30% glycol solutions. Analytical ultracentrifugation and turbidity data showed that IgG molecules do not aggregate at such concentrations of glycol. The complement-binding effect may be caused by a conformational transition in the IgG molecules.

Animals↗
PubMed1984

[Binding and activation of the first component of human complement on artificial matrices].

Artificial sorbents that comprise macroporous glass covered by the copolymer of N-vinylpyrrolidone and N-substituted acrylamide have been synthesized. Aminoethanol is bound to acrylic acid residue in one sorbent (AE-glass), whereas the other sorbent involves immunoglobulin G with the hexamethylenediamine spacer (IgG-glass). C1q binds specifically to IgG-glass with Ka 4,07(+/- 0,32) X 10(7) M-1. Free energy of the C1q binding to IgG-glass is twice higher than that of its binding to monomeric IgG. This evidences that one C1q molecule associates with two IgG molecules of the sorbent. A weak nonspecific sorption of C1q to AE-glass was found. Both specific (on IgG-glass) and nonspecific (on AE-glass) sorption of the first component of complement activate the classical pathway in human serum as manifested in the consumption of the C4, C2, C3 and C5 components. IgG-glass was employed for C1q isolation from human serum by affinity chromatography, whereas unbound part of serum may be used as a reagent R1q. The yield of highly purified C1q after IgG-glass affinity chromatography and gel filtration on Sephacryl S-300 is 63,6%.

Chemical Phenomena↗
PubMed1984

[A new low molecular-weight protein effector of human complement from the venom of the Central Asian cobra Naja naja oxiana].

Six protein effectors of human complement were isolated from the whole venom of the Central Asian cobra Naja naja oxiana. Three of them have acidic properties and molecular weights of 61 000, 5000 and 3000, and the rest are basic proteins with molecular weights of 54 000, 9000 and 7000. Two low molecular weight basic proteins CFB-II and CFB-III are isolated in as high amounts as 115 and 85 mg per g of dry venom. All the effectors inhibit the classical pathway of complement activation and, with the exception of CFB-II and CFB-III, the alternative pathway. The latter, on the contrary, enhances the alternative pathway of activation. N-Terminal sequence determination for CFB-III demonstrated its identity to the earlier characterized cytotoxin II. The action of CFB-III on the classical pathway of complement activation consists in the component C4 inactivation. A mechanism for the CFB-III activation of the alternative pathway is proposed implying the CFB-III induced transformation of the C3 component into a C3b-like one producing a soluble C3 convertase.

Chromatography, Gel↗
PubMed1983

[A mechanism of human complement activation by immunostimulators from the bacterial cell wall].

Effects on the human complement system of the cell wall preparations: lipopolysaccharides and polysaccharides of E. coli, Salmonella typhi (pyrogenal, salmosan), Bact. prodigiosum (prodigiosan) and peptidoglycan of Lactobacillus bulgaricus (blastolysin) have been studied. Lipopolysaccharide of E. coli, pyrogenal and salmosan were found to bind efficiently the first complement factor C1q. The constants for inhibition of the C1q binding to antibodies by the mentioned preparations were determined, and their ability to initiate the classical pathway of complement activation (consumption of C4, C2 and C3 factors) was assayed. These preparations only slightly affect the alternative pathway. Prodigiosan, not influencing the classical pathway, initiates the alternative one. Its binding constant with the activated Bb factor was determined. This constant reflects the Bb association with C3b and is (2,4 +/- 0,1) x 10(7) mole-1 l. Blastolysin is effective both in the C1q binding and initiation of the alternative pathway of complement activation. Immunostimulating activity of the bacterial cell wall preparations seems to involve activation of the complement system and the release of the fragments from the complement factors which are mediators of the immune response.

Anti-Bacterial Agents↗